Two Little Fishes MetaSorb UHC, 1-250 Gallon Capacity, is the solution for the excess of toxic heavy metals in your aquarium water. These toxic metals may come from the water source, from foods, from artificial seawater mixes, corroding metal equipment, magnets, pumps, etc. Sudden mysterious ailments in fishes, corals and other invertebrates may occur when heavy metals reach a toxic threshold. Two Little Fishes MetaSorb UHC is made with patented polymers developed for the US Environmental Protection Agency's Superfund Program. Insoluble in water and nontoxic, the polymers rapidly bind and permanently remove metals from fresh and saltwater, making it possible to restore the water quality. MetaSorb UHC is a fine powder that is packaged in a small cloth media bag that is easy to locate in any area where high volume water flow will facilitate the contact with the polymer. Simply place the bag in any canister filter, hang-on-the-back power filter, or in flow-through sections of any sump or filter chamber. After a few days MetaSorb UHC can be removed and discarded. For pre-treating new water or newly mixed artificial seawater MetaSorb UHC may be reused several times.